The invention concerns a raising device for attachment to hospital beds. A lifting device of this type is known for example from the disclosure of DE-OS No. 33 27 320.
Such raising devices are used particularly for patients who have just undergone operations or who are handicapped. In such a device the bedridden patient gets hold of a triangular grip and pulls himself up by it. An oval tube is in this case mounted to be pivotable in the support so that the patient can, by hanging on to the hand grip, swing himself to the edge of the bed by the rotation of the oval tube in the support. An anti-rotation clutch is provided to ensure the retention of the pivotable oval tube in any desired position of rotation in the support. By means of this, the oval tube is prevented from swinging too far and, for example, damaging objects near the bed.
In the case of the known raising device, the clutch consists of a dog clutch which can be engaged against the spring loading of a coil spring. A disadvantage of such an arrangement is that a locking of this clutch in desired intermediate positions is not possible, as because of the teeth positions of the engaging dog clutch, only specific angles of rotation can be locked.
A further disadvantage of this known raising device is that the clutch has a high rate of wear because the long leverage from the holding grip to the axis of rotation of the oval tube cause high torque loads to be transmitted to the clutch which leads to rapid wear of the dogs (teeth).